957 resultados para Branching Processes with Immigration


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Evidence of increasing concentrations of dissolved carbon dioxide, especially in the surface ocean and its associated impacts on calcifying organisms, is accumulating. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Hence, their response to an acidifying ocean may have important consequences for future inorganic carbon cycling. To assess the sensitivity of benthic foraminifera to changing carbon dioxide levels and subsequent alteration in seawater carbonate chemistry, we cultured specimens of the shallow water species Ammonia tepida at two concentrations of atmospheric CO2 (230 and 1900 ppmv) and two temperatures (10 °C and 15 °C). Shell weights and elemental compositions were determined. Impact of high and low pCO2 on elemental composition are compared with results of a previous experiment were specimens were grown under ambient conditions (380 ppvm, no shell weight measurements of specimen grown under ambient conditions are, however, available). Results indicate that shell weights decrease with decreasing [CO3], although calcification was observed even in the presence of calcium carbonate under-saturation, and also decrease with increasing temperature. Thus both warming and ocean acidification may act to decrease shell weights in the future. Changes in [CO3] or total dissolved inorganic carbon do not affect the Mg distribution coefficient. On the contrary, Sr incorporation is enhanced under increasing [CO3]. Implications of these results for the paleoceanographic application of foraminifera are discussed.

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Increased carbon dioxide (CO2) concentration in the atmosphere will change the balance of the components of carbonate chemistry and reduce the pH at the ocean surface. Here, we report the effects of increased CO2 concentration on the early development of the sea urchins Hemicentrotus pulcherrimus and Echinometra mathaei. We examined the fertilization, early cleavage, and pluteus larval stage to evaluate the impact of elevated CO2 concentration on fertilization rate, cleavage rate, developmental speed, and pluteus larval morphology. Furthermore, we compared the effects of CO2 and HCl at the same pH in an attempt to elucidate any differences between the two. We found that fertilization rate, cleavage rate, developmental speed, and pluteus larval size all tended to decrease with increasing CO2 concentration. Furthermore, CO2-seawater had a more severe effect than HCl-seawater on the fertilization rate. By contrast, the effects on cleavage rate, developmental speed, and pluteus larval morphology were similar for CO2- and HCl-seawater. Our results suggest that both decreased pH and altered carbonate chemistry affect the early development and life history of marine animals, implying that increased seawater CO2 concentration will seriously alter marine ecosystems. The effects of CO2 itself on marine organisms therefore requires further clarification.

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Ocean acidification (OA) is believed to be a major threat for near-future marine ecosystems, and that the most sensitive organisms will be calcifying organisms and the free-living larval stages produced by most benthic marine species. In this respect, echinoderms are one of the taxa most at risk. Earlier research on the impact of near-future OA on echinoderm larval stages showed negative effects, such as a decreased growth rate, increased mortality, and developmental abnormalities. However, all the long-term studies were performed on planktotrophic larvae while alternative life-history strategies, such as nonfeeding lecithotrophy, were largely ignored. Here, we show that lecithotrophic echinoderm larvae and juveniles are positively impacted by ocean acidification. When cultured at low pH, larvae and juveniles of the sea star Crossaster papposus grow faster with no visible affects on survival or skeletogenesis. This suggests that in future oceans, lecithotrophic species may be better adapted to deal with the threat of OA compared with planktotrophic ones with potentially important consequences at the ecosystem level. For example, an increase in populations of the top predator C. papposus will likely have huge consequences for community structure. Our results also highlight the importance of taking varying life-history strategies into account when assessing the impacts of climate change, an approach that also provides insight into understanding the evolution of life-history strategies.

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Ocean acidification and associated changes in seawater carbonate chemistry negatively influence calcification processes and depress metabolism in many calcifying marine invertebrates. We present data on the cephalopod mollusc Sepia officinalis, an invertebrate that is capable of not only maintaining calcification, but also growth rates and metabolism when exposed to elevated partial pressures of carbon dioxide (pCO2). During a 6 wk period, juvenile S. officinalis maintained calcification under ~4000 and ~6000 ppm CO2, and grew at the same rate with the same gross growth efficiency as did control animals. They gained approximately 4% body mass daily and increased the mass of their calcified cuttlebone by over 500%. We conclude that active cephalopods possess a certain level of pre-adaptation to long-term increments in carbon dioxide levels. Our general understanding of the mechanistic processes that limit calcification must improve before we can begin to predict what effects future ocean acidification will have on calcifying marine invertebrates.

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Ocean acidification and associated changes in seawater carbonate chemistry negatively influence calcification processes and depress metabolism in many calcifying marine invertebrates. We present data on the cephalopod mollusc Sepia officinalis, an invertebrate that is capable of not only maintaining calcification, but also growth rates and metabolism when exposed to elevated partial pressures of carbon dioxide (pCO2). During a 6 wk period, juvenile S. officinalis maintained calcification under ~4000 and ~6000 ppm CO2, and grew at the same rate with the same gross growth efficiency as did control animals. They gained approximately 4% body mass daily and increased the mass of their calcified cuttlebone by over 500%. We conclude that active cephalopods possess a certain level of pre-adaptation to long-term increments in carbon dioxide levels. Our general understanding of the mechanistic processes that limit calcification must improve before we can begin to predict what effects future ocean acidification will have on calcifying marine invertebrates.

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The aim of the paper is to analyze the impact of the economic crisis on the integration of the immigrant population in Spain. The Spanish case is singular because during the years of intense immigration achieved a remarkable degree of socio-cultural integration. The paper argues that such integration it has been the result of the confluence of exceptional factors rather than the result of the policy making. From a mixed methodology approach, it shows that, during the period of expansion, two factors of the immigration contribute to their coexistence with native population: finding job and access to public services. But the economic crisis, with its impact in terms of job losses and austerity policies, expose the weaknesses of the Spanish model of integration.

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A selected ion flow tube study of the reactions of a series of gas-phase atomic cations (S+, Xe+, O+, Kr+, N+, Ar+ and Ne+) and molecular ions (SF n+ (n = 1-5), CFn+ (n = 1-3), CF2Cl+, H3O+, NO+, N 2O+, CO2+, CO+, and N2+) spanning a large range of recombination energies (6.3-21.6 eV), with acetone, 1,1,1-trifluoroacetone, and hexafluoroacetone has been undertaken with the objective of exploring the nature of the reaction ion chemistry as the methyl groups in acetone are substituted for CF3. The reaction rate coefficients and product ion branching ratios for all 66 reactions, measured at 298 K, are reported. The experimental reaction rate coefficients are compared to theoretically calculated collisional values. Several distinct reaction processes were observed among the large number of reactions studied, including charge transfer (non-dissociative and dissociative), abstraction, ion-molecule associations and, in the case of the reactions involving the reagent ion H3O+, proton transfer. 

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SOUZA, Rodrigo B. ; MEDEIROS, Adelardo A. D. ; NASCIMENTO, João Maria A. ; GOMES, Heitor P. ; MAITELLI, André L. A Proposal to the Supervision of Processes in an Industrial Environment with Heterogeneous Systems. In: INTERNATIONAL CONFERENCE OF THE IEEEOF THE INDUSTRUI ELECTRONICS SOCIETY,32., Paris, 2006, Paris. Anais... Paris: IECON, 2006

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SOUZA, Rodrigo B. ; MEDEIROS, Adelardo A. D. ; NASCIMENTO, João Maria A. ; GOMES, Heitor P. ; MAITELLI, André L. A Proposal to the Supervision of Processes in an Industrial Environment with Heterogeneous Systems. In: INTERNATIONAL CONFERENCE OF THE IEEEOF THE INDUSTRUI ELECTRONICS SOCIETY,32., Paris, 2006, Paris. Anais... Paris: IECON, 2006

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Background: increasing numbers of patients are surviving critical illness, but survival may be associated with a constellation of physical and psychological sequelae that can cause on going disability and reduced health-related quality of life. Limited evidence currently exists to guide the optimum structure, timing, and content of rehabilitation programmes. There is a need to both develop and evaluate interventions to support and expedite recovery during the post-ICU discharge period. This paper describes the construct development for a complex rehabilitation intervention intended to promote physical recovery following critical illness. The intervention is currently being evaluated in a randomised trial (ISRCTN09412438; funder Chief Scientists Office, Scotland). Methods: the intervention was developed using the Medical Research Council (MRC) framework for developing complex healthcare interventions. We ensured representation from a wide variety of stakeholders including content experts from multiple specialties, methodologists, and patient representation. The intervention construct was initially based on literature review, local observational and audit work, qualitative studies with ICU survivors, and brainstorming activities. Iterative refinement was aided by the publication of a National Institute for Health and Care Excellence guideline (No. 83), publicly available patient stories (Healthtalkonline), a stakeholder event in collaboration with the James Lind Alliance, and local piloting. Modelling and further work involved a feasibility trial and development of a novel generic rehabilitation assistant (GRA) role. Several rounds of external peer review during successive funding applications also contributed to development. Results: the final construct for the complex intervention involved a dedicated GRA trained to pre-defined competencies across multiple rehabilitation domains (physiotherapy, dietetics, occupational therapy, and speech/language therapy), with specific training in post-critical illness issues. The intervention was from ICU discharge to 3 months post-discharge, including inpatient and post-hospital discharge elements. Clear strategies to provide information to patients/families were included. A detailed taxonomy was developed to define and describe the processes undertaken, and capture them during the trial. The detailed process measure description, together with a range of patient, health service, and economic outcomes were successfully mapped on to the modified CONSORT recommendations for reporting non-pharmacologic trial interventions. Conclusions: the MRC complex intervention framework was an effective guide to developing a novel post-ICU rehabilitation intervention. Combining a clearly defined new healthcare role with a detailed taxonomy of process and activity enabled the intervention to be clearly described for the purpose of trial delivery and reporting. These data will be useful when interpreting the results of the randomised trial, will increase internal and external trial validity, and help others implement the intervention if the intervention proves clinically and cost effective.

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Social anhedonia is a deficiency in the capacity to experience pleasure from social interactions. This study examined the implications of social anhedonia for romantic relationship functioning, including the association of social anhedonia with sentiments towards romantic partners that are central to relationship functioning (satisfaction, commitment, regard, and care), analogous perceptions of the partner’s sentiments, hostile behavior during relationship conflict, and perception of the partner’s hostile behavior. Data were collected from 281 participants who were involved in romantic relationships. Support was found for social anhedonia’s hypothesized negative association with satisfaction, regard, and care, as well as all four perceived partner sentiments. These associations were independent of attachment anxiety and avoidance. Additionally, attachment avoidance mediated social anhedonia’s relationship with commitment. However, no support was found for social anhedonia’s hypothesized positive association with actual and perceived partner hostile behavior. Results suggest that social anhedonia may undermine the functioning of interpersonal relationships.

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Immigration is directly related to citizenship, the nation and the state, revealing as it does the constructed nature of those categories. Here the impact of immigration on Euskal Herria is examined from this perspective, looking first at the processes of migration to it which have produced the make-up of present-day Basque society to a large extent. This is followed by a consideration of the way migratory movements have been viewed by the movement for the development of Euskal Herria into a state, the Basque nationalist movement, since these attitudes have played a fundamental role in defining Basque citizenship. After some observations about multiculturalism, the chapter concludes with a look at how the creation of a Basque state might contribute to this and the issues that will be raised.

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This study aimed to evaluate long-term atrophy in contralateral hippocampal volume after surgery for unilateral MTLE, as well as the cognitive outcome for patients submitted to either selective transsylvian amygdalohippocampectomy (SelAH) or anterior temporal lobe resection (ATL). We performed a longitudinal study of 47 patients with MRI signs of unilateral hippocampal sclerosis (23 patients with right-sided hippocampal sclerosis) who underwent surgical treatment for MTLE. They underwent preoperative/postoperative high-resolution MRI as well as neuropsychological assessment for memory and estimated IQ. To investigate possible changes in the contralateral hippocampus of patients, we included 28 controls who underwent two MRIs at long-term intervals. The volumetry using preoperative MRI showed significant hippocampal atrophy ipsilateral to the side of surgery when compared with controls (p<0.0001) but no differences in contralateral hippocampal volumes. The mean postoperative follow-up was 8.7 years (± 2.5 SD; median=8.0). Our patients were classified as Engel I (80%), Engel II (18.2%), and Engel III (1.8%). We observed a small but significant reduction in the contralateral hippocampus of patients but no volume changes in controls. Most of the patients presented small declines in both estimated IQ and memory, which were more pronounced in patients with left TLE and in those with persistent seizures. Different surgical approaches did not impose differences in seizure control or in cognitive outcome. We observed small declines in cognitive scores with most of these patients, which were worse in patients with left-sided resection and in those who continued to suffer from postoperative seizures. We also demonstrated that manual volumetry can reveal a reduction in volume in the contralateral hippocampus, although this change was mild and could not be detected by visual analysis. These new findings suggest that dynamic processes continue to act after the removal of the hippocampus, and further studies with larger groups may help in understanding the underlying mechanisms.